Curse of ancient Rome hangs over modern societies
August 13, 2008
By Etienne Swanepoel
Over time, all societies face problems of various kinds. In The Collapse of Complex Societies, Joseph Tainter advances the argument that societies respond to most problems by increasing societal complexity.
Generally, an increase in complexity results in an increase in energy expenditure. Initially, the benefits of complexity outweigh the additional expenditure. Over time, however, the costs will outweigh the benefits. In other words, the energy return on investment decreases. This is calculated by dividing the amount of energy a project produces by the amount it consumes.
Broadly, Tainter makes two points. First, complexity is expensive. Second, a society's investment in complexity to solve its problems eventually produces "diminishing marginal returns". In other words, at some point an additional investment in complexity provides fewer benefits than the immediately preceding investment.
Tainter illustrates his theory by applying it to the Roman Empire.
Like any ancient society, Rome was powered, in essence, by the sun's energy. It was a food-based energy system. Photosynthesis converted sunlight into energy suitable for human consumption in the form of agricultural produce.
Geographically, the Roman Empire became concentric. It first exploited the Mediterranean region's best cropland. Then it expanded and moved on to cultivate poorer lands. As its grain supply lines snaked further and further from its major cities, it had to work harder and harder to produce each additional ton of grain.
A complex society pursuing the expansion option, if it is successful, ultimately reaches a point where further expansion requires too high a marginal cost.
The borders at the periphery increase substantially. Among other things, the size of area to be administered, its administration costs and the presence of competitors converge and depress further growth.
This perfectly illustrates the declining marginal return problem.
According to Tainter, ancient societies addressed this problem by capturing a new energy subsidy. This was accomplished by territorial expansion, as with the Roman Empire. It resulted in the creation of an immensely complex social system.
But due to declining marginal returns, the Roman Empire was eventually unable to generate enough high-quality energy to support its social complexity. So in a food-based energy system, the energy subsidy initially obtained from geographical expansion eventually declines.
According to Thomas Homer-Dixon in The Upside of Down, decay inevitably sets in around the periphery. From there it spreads to the centre, slowly engulfing the empire in chaos.
In short, the Roman Empire experienced an irreversible energy crisis. In theory, had the empire possessed the technical fecundity to switch to an energy system with higher calorific values, such as fossil fuels, it would have extended its life considerably. Due to declining marginal returns, the margin of tolerance decreased and it was less able to cope with the exogenous shocks imposed, for example, by the barbarians eating away at the periphery.
The Roman army was divided into hundreds of encampments along the periphery to prevent the barbarians from enveloping Rome. Unfortunately for Rome, it was unable to engage in any decisive battle; multiple small targets spread over a wide geographical area prevented this. The barbarians at the periphery benefited from the increased energy costs and the declining marginal returns faced by the Romans.
Decay at the periphery was arguably a direct result of the energy shortage experienced by the Roman Empire.
At the end of the day, the energy cost of the complexity of the Roman Empire was too great for a food-based energy system. Failure was inevitable.
It is tempting to apply Tainter's model to the predicament faced by the world today. There is seemingly a similarity between the declining marginal returns from the prevailing fossil fuel energy system and the declining marginal returns from defending the periphery of the Roman Empire.
First, the Achilles heel of the current energy system is the environmental effects of carbon dioxide emissions.
Second, the bulk of oil reserves is in countries hostile or potentially hostile to the West. At some stage, the marginal returns of doing business with these oil producers will become negative.
Unlike the Roman Empire, there is no territorial expansion strategy available to the developed world, unless the US occupation of Iraq is viewed in that light. If this is the case, the cost of declining US prestige across much of the world that is attributable to the Iraq War contributes to the declining marginal returns associated with the use of oil.
This applies to all consumers inasmuch as increases in geopolitical risk of this scale are not localised to the US but are of general application.
It is arguable that the core and periphery argument also has application today: the periphery is unstable today in view of emissions and the geographical location of oil reserves.
The upshot is that apart from the typical economic and climate change analysis applied to demonstrate the fault lines of an oil energy platform, a philosophical analysis of the type proposed by Tainter and Homer-Dixon also hits the mark.
Etienne Swanepoel is a partner at Webber Wentzel. The views expressed in this column are his own
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